如何在Node.js插件中泵送窗口消息? [英] How do I pump window messages in a nodejs addon?

问题描述

在Windows nodejs插件中，我创建了一个用于接收消息的窗口.

In a Windows nodejs addon, I've created a window for the purpose of receiving messages.

Handle<Value> MakeMessageWindow(const Arguments &args) { // exposed to JS
    ...
    CreateWindow(L"ClassName", NULL, 0, 0, 0, 0, 0, HWND_MESSAGE, 0, 0, 0);
    ...
}

我有一个wndproc函数.

I have a wndproc function.

Local<Function> wndProc;
LRESULT APIENTRY WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    // pack up the arguments into Local<Value> argv
    wndProc->Call(Context::GetCurrent()->Global(), 3, argv);
}

现在我需要发送消息.通常，您会做类似的事情

Now I need to pump messages. Normally, you'd do something like

MSG msg;
while (GetMessage(&msg, NULL, 0, 0)) 
{
     TranslateMessage(&msg);
     DispatchMessage(&msg);
}

...但是由于它只会阻止v8事件循环，因此不起作用.

...but that won't work since it would just block the v8 event loop.

如何以不会阻塞v8的方式泵送Windows消息，并允许我的窗口接收消息时调用JS函数?

How do I pump Windows messages in a manner that won't block v8 and allows me to invoke a JS function when my window receives messages?

我假设libuv将起作用，但是我不确定如何从在单独线程上运行的C安全地调用JS函数，尤其是因为

I presume libuv will play a role, but I'm unsure exactly how to safely invoke a JS function from C running on a separate thread, especially since uv_async_send is not guaranteed to invoke a callback every time you call it, and I need to ensure that my JS callback is called every time a window message is received.

推荐答案

我的错误是试图在V8线程上创建窗口.相反，应该使用 uv_thread_create 调用一个函数，该函数在新线程上创建窗口 ，然后继续执行其自己的消息泵循环.

My mistake was trying to create the window on the V8 thread. Instead, uv_thread_create should be used to call a function that creates the window on a new thread and then proceeds to do its own message pump loop.

然后，wndproc函数需要以线程安全的方式将接收到的消息保存到队列中，然后使用 uv_async_send 通知V8线程消息已到达.

The wndproc function then needs to save received messages into a queue in a thread-safe manner and then use uv_async_send to notify the V8 thread that messages have arrived.

消息入队后，将调用V8线程上的一个函数(该函数已传递给 uv_async_init ).该功能(线程安全)将每个待处理的消息从队列中弹出，并调用JS回调.

A function on the V8 thread (which was passed to uv_async_init) is then invoked after messages are enqueued. The function (thread-safely) pops each pending message off the queue and invokes the JS callback.

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